It is well understood from the perspective of phonetics.
[h] is the most natural consonant of human beings. The essence of [h] is exhalation. The air flow in the lungs does not drive the vocal cord to vibrate. It passes directly through the mouth without any hindrance, and it emits [h]. All other consonants can be regarded as deformations of airflow on the basis of [h], with the addition of vocal cord vibration, friction, obstruction and other modifications. In fact, [h] is also considered as a “silent vowel” rather than a consonant in the phonetic world.
[a] is the most natural vowel of human beings, that is to say, the anatomical structure of human oral cavity determines that as long as the mouth is opened and the air flow in the lungs drives the natural vibration of vocal cords, the sound produced is [a]. In other words, if human beings want to make a sound (the vocal cords must vibrate), the most natural sound is [a]. All other vowels are deformed by the adjustment of tongue position, round lip, opening degree and nasalization of [a]. So almost all the phonetic alphabets in the world begin with the symbols that represent the pronunciation of [a]. It can be said that [a] is the foundation of human speech.
When humans laugh, the state of vocalization is the most relaxed and natural. The vocal organs do not need any modification. At the same time, they must make a sound to express their laughter. That is obviously the most direct combination. This can be seen as the continuous outgassing of the lungs, the continuous flow of air to drive the vocal cords, while the oral region does not add other actions, resulting in a periodic combination of H + a.
The phonology of a language may lack the consonant phoneme [h], but as long as humans can breathe, they should not fail to produce [h]. Character tables, such as Mandarin and Spanish soft palate fricative [x], and even Korean felts, are only written records of laughter, and do not represent actual pronunciation. In fact, the word “ha” was reintroduced to fill in the phonemic correspondence of “xa” which is the closest phoneme to laughter in Putonghua. The onomatopoeia of Chinese characters used for laughter is originally “ha”, which corresponds to the sound of “ha”.
In addition, in the context of the situation, not the most natural state of laughter, consonants, vowels will be adjusted accordingly, consonants with a little friction may become soft palate fricative, small tongue fricative and even soft palate stopper [k], vowels through loudness adjustment (suppressing the volume of laughter) is the central vowel “ha”, through opening adjustment. (Pressing the expression) becomes a closed vowel [i] “hip-hop”.
The more unconscious a laugh is, such as a sudden “laugh” when you see something too funny, or a laugh that you can’t suppress, the closer it gets to the natural “ha” sound. But when you ask the laugher to pronounce the standard “ha” when talking, people who lack the consonant [h] phoneme really don’t necessarily pronounce it. From this point of view, A and HA can be regarded as the instinctive sound of human beings, which is one level lower than the actual language.
In fact, it is not just laughter. When people are in a state of high relaxation, fatigue, or expressing surprise, such as breathing in a state of fatigue or surprise, the exclamation is almost HA or aha, because when a person’s vocal organ is highly relaxed, or something happens suddenly too late to mobilize the oral vocal organ, but it needs to be issued. When there are enough sounds, the basic ones that can be emitted are a and ha.